Bacteriocinogenic plasmids of Bacillus thuringiensis

When strains of Bacillus thuringiensis v. morrisoni or v. darmstadiensis were plated on solid medium, the appearance of oligosporogenic (Ospo) mutants and bacteriocin non-producing clones (Thc-) was observed. The comparative analysis of the plasmid content of original and mutant strains revealed that the appearance of Ospo and Thc- phenotypes correlated with the loss of certain plasmids.